Heat sink and multi-directional passages thereof

ABSTRACT

A heat sink comprises a plurality of heat-dissipating units, and each heat-dissipating unit provides a base and a plurality of parallel fins disposed thereon, respectively. The fins of any two adjacent heat-dissipating units extend in different directions.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a heat sink, and in particular to a heat sink providing multi-directional passages.

2. Description of the Related Art

Heat dissipation devices or systems have been widely applied in electronic products such as personal and notebook computers, to dissipate heat generated by components or microprocessors, such as an integrated circuit disposed therein. Due to the gradual decrease in size of the integrated circuit and advanced packing, however, heat generated per unit area thereof correspondingly increases. Thus high-performance heat dissipation devices or heat sinks are indispensable for the described products.

FIG. 1A shows a conventional heat dissipation device 10 comprising an axial-flow fan 20 and a fin structure 30. The axial-flow fan 20 comprises a frame 22, a hub 24 and an impeller 26 disposed thereon. The fin structure 30 has a base 32 and a plurality of fins 34 disposed on the base 32. The impeller 26 has a plurality of blades, and the fins 34 of the fin structure 30 extend in a Y-direction of an X-Y rectangular coordinate system.

After installing the axial-flow fan 20 on the fin structure 30, the bottom surface of the fin structure 30 of the heat dissipation device 10 is centrally disposed onto a component such as a CPU (not shown). The hub 24 of the axial-flow fan 20 is disposed on the center of the fin structure 30, and the blades of the impeller 26 are located along the peripheral edge of the fin structure 30.

During operation, heat generated from the CPU is transmitted to the fins 34 via the base 32, and heat on the fins 34 is dissipated by airflow driving by the fan 20. Temperature at the center of the base 32 of the fin structure 30 is highest, gradually decreasing toward the periphery thereof.

It is noted that the center of the fin structure 30 is located below the hub 24 of the fan 20, and performance of heat dissipation at the center of the fin structure 30 is far lower than that at the periphery thereof, i.e., the heat dissipation of the center of the fin structure 30 is affected by the hub 24 of the fan 20.

Furthermore, due to the longitudinal direction of the fins 34 of the fin structure 30 extending in a Y-direction, airflow driving by the fan 20 flows partially along the passages formed among the fins 34, partially impacting the fins 34 in the X-direction (the direction normal to the Y-direction). Parts of the airflow collide with each other, decreasing smoothness thereof and cooling speed of the heat dissipation device 10. Effect of heat dissipation at the center of the fin structure 30 is also decreased.

FIG. 1B shows another conventional heat dissipation device 50 comprises a fin structure 70 and the axial-flow fan 20 mentioned above. The fin structure 70 differs from the fin structure 30 of FIG. 1A in that a plurality of spaced slots 740 are formed on the fins 74 in the X-direction, i.e., the slots 740 function as airflow passages in the X-direction of the fin structure 70. Thus, more airflow can smoothly enter the center of the fin structure 70 via the passages formed in the X- and Y-directions of the fin structure 70.

In comparison with the fin structure 30 of FIG. 1A, an effective dissipative area of the fin structure 70 is less than that of the fin structure 30 by about 30% due to the slots 740 formed on the fins 74. Although the formation of the slots 740 can allow airflow to enter the center of the fin structure 70 in the X- and Y-directions, the loss of dissipative area on the fin structure 70 reduces convection of the heat dissipation device 50. Furthermore, airflow in the passages in the X- and Y-directions collides, increasing resistance of airflow as well as decreasing flow rate and volume of airflow output from the fins 74.

SUMMARY OF THE INVENTION

Accordingly, an object of the invention is to provide a heat sink to overcome the problems of the above described fin structure.

The invention comprises a plurality of heat-dissipating units, each of which comprises a base and a plurality of parallel fins disposed on the base. The fins of any two adjacent heat-dissipating units extend in different directions to form multi-directional passages therebetween. Thus collision of airflow in the passages of each heat-dissipating unit does not occur.

Each heat-dissipating unit of the heat sink further comprises a welding region located at the periphery of the base thereof to connect to another heat-dissipating unit. The base and fins of the heat-dissipating unit are integrally formed and made of copper, copper alloy, aluminum or aluminum alloy. The base and fins of the heat-dissipating unit are also connected to each other by welding.

The heat-dissipating unit further comprises a plurality of slots formed on an upper surface of the base thereof. The fins are snugly disposed in the slots to form the passages therebetween.

The base of the heat-dissipating unit comprises a polygonal column with at least three faces, such as triangular, sectorial, pentagonal and hexagonal. Any two adjacent heat-dissipating units are connected to by welding. The bases of each heat-dissipating unit are connected via a low thermo-resistant conductive adhesive or glue. The base and fins of the heat-dissipating units are made of a conductive material.

Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings, which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:

FIG. 1A is a perspective view of a conventional heat-dissipation device;

FIG. 1B is a perspective view of another conventional heat-dissipation device;

FIG. 2A is a perspective view of a heat-dissipation device according to a first embodiment of the present invention;

FIG. 2B(1) is a perspective view of the heat-dissipation device of FIG. 2A;

FIG. 2B(2) is an exemplary of the heat-dissipating unit of FIG. 2A;

FIG. 2C is a perspective view of a heat-dissipation device according to a second embodiment of the present invention;

FIG. 3A is a perspective view of a heat-dissipation device according to a third embodiment of the present invention;

FIG. 3B is a perspective view of the heat-dissipation device of FIG. 3A;

FIG. 3C is a perspective view of a heat-dissipation device according to a fourth embodiment of the present invention;

FIG. 4 is a perspective view of a heat-dissipation device according to a fifth embodiment of the present invention;

FIG. 5 is a perspective view of a heat-dissipation device according to a sixth embodiment of the present invention; and

FIG. 6 is a perspective view of a heat-dissipation device according to a seventh embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In the preferred embodiment of the present invention, the heat sink assembled with an electrical fan (not shown in FIGS.) is capable of dissipating heat from components or devices thereof.

Referring to FIGS. 2A and 2B, in a first embodiment of the invention, a heat sink 100 comprises four heat-dissipating units 102, 104, 106 and 108. Each heat-dissipating unit 102, 104, 106 and 108 respectively comprises a base 112, 114, 116 and 118, and a group of parallel fins 122, 124, 126 and 128 is disposed on the base 112, 114, 116 and 118. The fins 122, 124, 126 and 128 individually extend in different directions with respect to the X-Y rectangular coordinate system.

The heat-dissipating units 102, 108 are two opposite and symmetrical polygonal structures, substantially triangular shaped. In FIG. 2B, each base 112, 118 of the heat-dissipating units 102, 108 is substantially triangular, i.e., each base 112, 118 provides three faces.

The heat-dissipating units 104, 106 are two opposite and symmetrical polygonal structures, next to the heat-dissipating units 102, 108 and are substantially pentagonal. In FIG. 2B, each base 114, 116 of the heat-dissipating units 104, 106 is substantially formed in a pentagonal column, i.e., each base 114, 116 provides five faces. Any two fins 122, 124, 126 and 128 as well as any two bases 112, 114, 116 and 118 of the heat-dissipating units 102, 104, 106 and 108 are connected along two faces, i.e., the welding regions 115. That is to say, the heat-dissipating units 104, 106 are connect to both the heat-dissipating units 102 and 108 at the periphery thereof by welding. In other words, the longitudinal directions of fins 122/124, 122/126, 128/124 and 128/126 of the adjacent heat-dissipating units 102/104, 102/106, 108/104 and 108/106 are perpendicularly connected to form a plurality of passages therebetween.

Furthermore, each heat-dissipating unit 104, 106 comprises two extended portions 130, 130, extending from the bases 114, 116 thereof and each having a hook 132 thereon. By connecting the hooks 132 of each extended portion 130 of the heat-dissipating units 104, 106 to the electrical fan, the electrical fan fixed on the heat-dissipating units 102, 104, 106 and 108 is located at the center of the heat sink 100.

In this embodiment, for example, the base 112 and the fins 122 of the heat-dissipating unit 102 are integrally formed, constructing multi-directional passages. The base and fins of each heat-dissipating unit are preferably made of conductive materials such as copper, copper alloy, aluminum or aluminum alloy. In other embodiments, the fins can be welded to the base to form the multi-directional passages thereon, i.e., one passage is formed by two adjacent fins.

In FIG. 2A, the passages of each heat-dissipating unit 102, 104, 106 and 108 respectively extend in different directions with respect to the X-Y rectangular coordinate system. That is to say, the heat sink 100 provides multi-directional passages on the XY plane of the X-Y rectangular coordinate system. A positive X-direction defines the longitudinal direction of the fins 122 of the heat-dissipating unit 102, and a negative X-direction defines the longitudinal direction of the fins 128 of the heat-dissipating unit 108. A positive Y-direction defines the longitudinal direction of the fins 126 of the heat-dissipating unit 106, and a negative Y-direction defines the longitudinal direction of the fins 124 of the heat-dissipating unit 104.

Thus, the longitudinal direction of the fins 122 of the heat-dissipating unit 102 is perpendicular to both the fins 124 of the heat-dissipating unit 104 and the fins 126 of the heat-dissipating unit 106, and the longitudinal direction of S the fins 128 of the heat-dissipating unit 108 is also perpendicular to both the fins 124 of the heat-dissipating unit 104 and the fins 126 of the heat-dissipating unit 106. In other words, the connected fins 122/124 of the heat-dissipating units 102/104, the connected fins 122/126 of the heat-dissipating units 102/106, the connected fins 128/126 of the heat-dissipating units 108/106 and the connected fins 128/124 of the heat-dissipating units 108/104 are all L-shaped.

During operation, the electrical fan drives airflow to enter all passages of the heat-dissipating units 102, 104, 106 and 108 to displace heat thereof. The airflow then flows out of the heat sink 100 along the passages from the center to the periphery thereof, evenly and radially. Heat located at the center of the heat sink 100 is efficiently dissipated and carried by the airflow in different directions.

With the fins 122, 124, 126 and 128, area for dissipation increases, and airflow from the electrical fan is evenly guided by each heat-dissipating unit 102, 104, 106 and 108, so that heat from the heat sink 100, especially from the center, is quickly dissipated. Furthermore, collision, turbulence or interference is prevented, thus increasing heat-dissipating efficiency of the heat sink 100.

In FIG. 2B(2), an exemplary of the heat-dissipating unit 104 a of FIG. 2A, a plurality of spaced slots 1140 are formed on the upper surface 1141 of the base 114 c of a heat-dissipating unit 104 c. A plurality of fins 124 c are inserted into the slots 1140 to form the passages therebetween, respectively.

In other preferred embodiments, any two bases 112, 114, 116 and 118 of the heat-dissipating units 102, 104 a, 106 and 108 can be connected along two faces thereof via a low thermo-resistant conductive adhesive or glue 145 such as solder paste.

Referring to FIG. 2C, in a second embodiment, a heat sink 150 differs from the heat sink 100 of the first embodiment in that four posts 140′ respectively extend from the bottom thereof, and a conductive plate 140 confined by the posts 140′ is further provided to attach to the bottom thereof, i.e., the conductive plate 140 is directly attached on the outer surface of the bases 112 b, 114 b, 116 b and 118 b of the heat-dissipating units 102 b, 104 b, 106 b and 108 b. In this embodiment, the conductive plate 140 is preferably made of copper or copper alloy.

When the conductive plate 140 is disposed on a component such as a CPU (not shown), the heat sink 150 thereof is, directly and centrally, attached to the top surface of the CPU, and thus heat from the CPU is directly transmitted to each heat-dissipating unit 102 b, 104 b, 106 b and 108 b via the conductive plate 140.

Furthermore, a low thermo-resistant conductive adhesive or glue 145 such as solder paste is disposed between the conductive plate 140 and each heat-dissipating unit 102 b, 104 b, 106 b and 108 b, i.e., the heat-dissipating units 102 b, 104 b, 106 b and 108 b are also connected via the conductive adhesive or glue 145. Thus, with the conductive adhesive or glue 145 disposed between the conductive plate 140 and the heat-dissipating units 102 b, 104 b, 106 b and 108 b, reduces heat resistance therebetween, and therefore heat flux from the CPU to the heat sink 150 increases. The bases 112 b, 114 b, 116 b and 118 b of the heat-dissipating units 102 b, 104 b, 106 b and 108 b is substantially sectorial.

Referring to FIGS. 3A and 3B, in a third embodiment, a heat sink 200 differs from the heat sink 100 of the first embodiment in that the number of heat-dissipating units is three, marked by reference numerals 202, 204 and 208, where the heat-dissipating unit 202 is a single structure, substantially integrated by the heat-dissipating units 104 and 106 of the first embodiment.

Each heat-dissipating unit 202, 204 and 208 comprises a base 212, 214 and 218 and three groups of parallel fins 222, 224 and 228 respectively disposed on the base 212, 214 and 218. The base 212 of the heat-dissipating unit 202 is formed in an hourglass spaced column, and the fins 222 thereon extend in the Y-axis on the XY plane. The heat-dissipating unit 202 comprises four extended portions 230, extending from the bases 212 thereof and each having a hook 232 thereon, providing the same function as the extended portions and hook mentioned above.

The fins 222 of the heat-dissipating unit 202 are perpendicularly connected to both fins 224, 228 of the heat-dissipating unit 204, 208, respectively. The

Any two 222, 224 and 228 as well as any two bases 212, 214 and 218 of the heat-dissipating units 202, 204 and 208 are connected along welding regions 215.

In this embodiment, for example, the base and fins of the heat-dissipating unit are integrally formed, preferably made of conductive materials such as copper, copper alloy, aluminum or aluminum alloy. In other embodiments, the fins can be welded to the base to form the multi-directional passages thereon, i.e., one passage is formed by two adjacent fins.

In other preferred embodiments, any two bases 212, 214 and 218 of the heat-dissipating units 202, 204 and 208 can be connected along faces thereof via a low thermo-resistant conductive adhesive or glue 245 such as solder paste.

Referring to FIG. 3C, in a fourth embodiment, a heat sink 250 differs from the heat sink 200 of the third embodiment in that four posts 240′ respectively extend from the bottom thereof, and a conductive plate 240 confined by the posts 240′ is further provided to attach to the bottom thereof, i.e., the conductive plate 240 is directly attached to the outer surface of the bases 212, 214 and 218.

In this embodiment, the conductive plate 240 is preferably made of copper or copper alloy. A low thermo-resistant conductive adhesive or glue 245 is disposed between the conductive plate 240 and each heat-dissipating unit 202, 204 and 208, i.e., the heat-dissipating units 202, 204 and 208 are also connected via the conductive adhesive or glue 245.

Referring to FIG. 4, in a fifth embodiment of the invention, a heat sink 300 comprises four heat-dissipating units 302, 304, 306 and 308, substantially comprising a rectangular column or shape. Each heat-dissipating unit 302, 304, 306 and 308 have the same rectangular structure.

For example, each heat-dissipating unit 302, 304 and 306 comprises a base 312, 314, 316 and a group of parallel fins 322, 324 and 326. The fins 322, 324, 326 are vertically disposed on the base 312, 314 and 316, respectively. The bases 312, 314, and 318 of the heat-dissipating units 302, 304 and 308 are substantially formed in rectangular, i.e., each base 312, 314, 316 provides four faces. When the fins 322/324, 322/326, 328/324, 328/326 and the base 312/314, 312/316 of the heat-dissipating units 302, 304 and 306 are connected by welding or a welding region 315, respectively, the heat-dissipating unit 302 connects to both heat-dissipating units 304 and 306 along two faces, respectively.

By welding the heat-dissipating units 302, 304, 306 and 308 to form the heat sink 300, the fins 322, 324, 326 and 328 individually extend in different directions with respect to the X-Y rectangular coordinate system. In other words, the passages of each heat-dissipating unit 302, 304, 306 and 308 respectively extend in different directions with respect to the X-Y rectangular coordinate system. A positive X-direction defines the longitudinal direction of the fins 326 of the heat-dissipating unit 306, and a negative X-direction defines the longitudinal direction of the fins 324 of the heat-dissipating unit 304. A positive Y-direction defines the longitudinal direction of the fins 328 of the heat-dissipating unit 308, and a negative Y-direction defines the longitudinal direction of the fins 322 of the heat-dissipating unit 302.

Thus, the longitudinal direction of the fins 322 of the heat-dissipating unit 302 is perpendicular to both the fins 324 of the heat-dissipating unit 304 and the fins 326 of the heat-dissipating unit 306, and the longitudinal direction of the fins 328 of the heat-dissipating unit 308 is also perpendicular to both the fins 324 of the heat-dissipating unit 304 and the fins 326 of the heat-dissipating unit 306.

In other preferred embodiments, base 312/314, 312/316 of the heat-dissipating units 302, 304 and 306 can be connected to each other via a low thermo-resistant conductive adhesive or glue 345 such as solder paste.

In this embodiment, for example, the base and fins of the heat-dissipating unit are integrally formed, preferably made of conductive materials such as copper, copper alloy, aluminum or aluminum alloy. In other embodiments, the fins can be welded to the base to form the multi-directional passages thereon, i.e., one passage is formed by two adjacent fins.

A conductive plate, preferably made of copper or copper alloy, is further provided to attach to the bottom of the heat sink 300 in the same way as the one mentioned in the description of heat sinks 100, 200, and a low thermo-resistant conductive adhesive or glue is disposed therebetween.

Referring to FIG. 5, in a sixth embodiment of the invention, a heat sink 400 comprises six heat-dissipating units 402, 404, 406, 408, 410 and 412, substantially forming a hexagonal column or shape. Each heat-dissipating unit 402, 404, 406, 408, 410 and 412 has the same triangular structure.

For example, each heat-dissipating unit 402, 404 and 412 comprises a base 422, 424, 432 and a group of parallel fins 442, 444 and 452. The fins 442, 444 and 452 are vertically disposed on the bases 422, 424 and 432, respectively. The bases 422, 424 and 432 of the heat-dissipating units 402, 404 and 412 are substantially triangular, i.e., each base 422, 424 and 432 provides three faces.

When the fins 442/444, 442/452 and the base 422/424, 422/432 of the heat-dissipating units 402, 404 and 412 are connected other by welding or a welding region 415, two faces of the heat-dissipating unit 402 are connected to both heat-dissipating units 404 and 412, respectively. The fins 442, in addition to the middle one, connect to each fin 444, 452 of the heat-dissipating units 404 and 412, respectively, to form a plurality of V-shaped passages therebetween. That is to say, the fins 442, 444, 446, 448, 450 and 452 extend in different directions on the XY plane, and a 60 degree angle exists between any two longitudinal directions of the fins 442, 444, 446, 448, 450 and 452 of the heat-dissipating units 402, 404, 406, 408, 410 and 412.

In other preferred embodiments, the base 422/424, 422/432 of the heat-dissipating units 402, 404 and 412 can be connected to each other via a low thermo-resistant conductive adhesive or glue 445 such as solder paste.

A conductive plate, preferably made of copper or copper alloy, is further provided to attach to the bottom of the heat sink 400 in the same way as the one mentioned in the description of heat sink 100, 200 and 300, and a low thermo-resistant conductive adhesive or glue is disposed therebetween.

Referring to FIG. 6, in a seventh embodiment of the invention, a heat sink 500 comprises three heat-dissipating units 502, 504 and 506, substantially forming a rectangular column or shape. Each heat-dissipating unit 502, 504 and 506 has a rectangular structure, and the heat-dissipating units 502 are disposed between the heat-dissipating units 504 and 506.

Each heat-dissipating unit 502, 504 and 506 comprises a base 512, 514, 516 and a group of parallel fins 522, 524 and 526. The fins 522, 524 and 526 are vertically disposed on the bases 512, 514, 516, respectively. The bases 512, 514, 516 of the heat-dissipating units 502, 504 and 506 are substantially rectangular, i.e., each base 512, 514, 516 provides four faces. In the preferred embodiment, the base 512 of the heat-dissipating unit 502 is square, and the longitudinal direction of the fins 522 is perpendicular to both the fins 524 of the heat-dissipating unit 504 and the fins 526 of the heat-dissipating unit 506. The fins 522/524, 522/526 and the base 512/514, 512/516 of the heat-dissipating units 502, 504 and 506 are connected by welding or a welding region 515, respectively.

By welding the heat-dissipating units 502, 504 and 506 to form the heat sink 500, the fins 522 and 524 or the fins 522 or 526 individually extend in different directions with respect to the X-Y rectangular coordinate system. The passages of each heat-dissipating unit 502, 504 and 506 respectively extend in different directions with respect to the X-Y rectangular coordinate system. A positive and negative X-direction define the longitudinal direction of the fins 522 of the heat-dissipating unit 502. A positive Y-direction defines the longitudinal direction of the fins 526 of the heat-dissipating unit 506, and a negative Y-direction defines the longitudinal direction of the fins 524 of the heat-dissipating unit 504.

In other words, the longitudinal directions of fins 522/524 and 522/526 of the adjacent heat-dissipating units 502/504 and 502/506 are perpendicularly connected to form a plurality of passages therebetween.

In other preferred embodiments, 512/514, 512/516 of the heat-dissipating units 502, 504 and 506 can be connected to each other via a low thermo-resistant conductive adhesive or glue 545 such as solder paste.

In this embodiment, for example, the base and fins of the heat-dissipating unit are integrally formed, preferably made of conductive materials such as copper, copper alloy, aluminum or aluminum alloy. In other embodiments, the fins can be welded to the base to form the multi-directional passages thereon, i.e., one passage is formed by two adjacent fins; a plurality of spaced slots (not shown in FIGS.) can also be formed on the upper surface of the bases. The fins are inserted into the slots to form the passages therebetween, respectively.

A conductive plate, preferably made of copper or copper alloy, is further provided to attach to the bottom of the heat sink 500 in the same way as the one mentioned in the description of heat sink 100, 200, 300 and 400, and a low thermo-resistant conductive adhesive or glue is disposed therebetween.

Furthermore, in the other embodiments, the bases of the heat-dissipating units can be polygonal structures, such as sectorial, isosceles triangular or other structures to form the heat sinks, so that heat aggregated at the center of the heat sink is quickly dissipated and carried by airflow flowing along different passages, i.e., temperature of the center and periphery of the base of the heat sink are close. No airflow collisions occur in the passages of the heat-dissipating units.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to accommodate various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 

1. A heat sink, comprising: a plurality of heat-dissipating units, each of which provides a base and a plurality of parallel fins disposed on the base, wherein the fins of any two adjacent heat-dissipating units are connected and extended in different directions individually.
 2. The heat sink as claimed in claim 1, wherein each heat-dissipating unit further comprises a welding region located at the periphery of the base thereof to connect to another heat-dissipating unit.
 3. The heat sink as claimed in claim 1, wherein the base and the fins of the heat-dissipating unit are integrally formed.
 4. The heat sink as claimed in claim 3, wherein the base and the fins of the heat-dissipating unit are made of copper, copper alloy, aluminum or aluminum alloy.
 5. The heat sink as claimed in claim 1, wherein the base and the fins of the heat-dissipating unit are connected by welding.
 6. The heat sink as claimed in claim 5, wherein the base and the fins of the heat-dissipating unit are made of copper, copper alloy, aluminum or aluminum alloy.
 7. The heat sink as claimed in claim 1, wherein the heat-dissipating unit further comprises a plurality of slots formed on an upper surface of the base thereof, and the fins are disposed in the slots respectively.
 8. The heat sink as claimed in claim 1, wherein the base of the heat-dissipating unit comprises a polygonal column with at least three faces.
 9. The heat sink as claimed in claim 1, wherein the base of the heat-dissipating unit comprises a sectorial column.
 10. The heat sink as claimed in claim 1, wherein any two adjacent heat-dissipating units are connected by welding.
 11. The heat sink as claimed in claim 1, wherein the bases of each heat-dissipating unit are connected via a low thermo-resistant conductive adhesive or glue.
 12. The heat sink as claimed in claim 1, wherein the fins of any two adjacent heat-dissipating units are substantially orthogonally connected.
 13. The heat sink as claimed in claim 1, wherein the heat-dissipating unit comprises a plurality of straight fins.
 14. The heat sink as claimed in claim 1, wherein the fins of the heat-dissipating unit are not curved.
 15. A heat sink, comprising: a plurality of heat-dissipating units, each of which provides a base and a plurality of parallel fins disposed on the base, wherein no gap exists between the connected fins of any two adjacent heat-dissipating units.
 16. The heat sink as claimed in claim 15, wherein the heat-dissipating unit comprises a plurality of straight fins.
 17. The heat sink as claimed in claim 15, wherein the fins of the heat-dissipating unit are not curved. 